Definition of MILK THISTLE
- » sow thistle: any of several Old World coarse prickly-leaved shrubs and subshrubs having milky juice and yellow flowers; widely naturalized; often noxious weeds in cultivated soil
- » lady's thistle, Our Lady's mild thistle, holy thistle, blessed thistle, Silybum marianum: tall Old World biennial thistle with large clasping white-blotched leaves and purple flower heads; naturalized in California and South America
